solving scc_main_lemma_1_4: solving scc properties
solving scc_lemma_1_4: solved a relation lemma (1_4_1_1_2_1_3)
solving scc_lemma_1_4: more scc properties
solving scc_lemma_1_4: scc properties
defined new version of single_child_ancestors
solvin scc_lemma_1_4: 1_4_3
solving scc_lemma_1_4 : 1_4_3
solving scc_main_lemma_1_4
solving scc_lemma_1_4
solving scc_lemma_1_4
solving scc_main_lemma_1_4
solving scc_lemma_4
solving scc_lemma_1_4
solving scc_lemma_4
solving scc_lemma_1_4
solving scc_lemma_4
solving scc_lemma_1_4
solving scc_lemma_4
solving scc_lemma_1_4
solving scc_lemma_1_4